Lately I have been pondering ways that I could demonstrate the differences between the different options that we can vote on in the referendum coming up in November. Last week I thought that a good way of doing this would be to take the historical voting data from Hamilton East and run it through the various systems so that people would be able to see the consequences of changing the system.
Anyway below is the results from Hamilton East under the different systems and a summary of what you will find.
MMP is a proportional system and as can be seen in these results comes fairly close to giving each party fair representation, the fact that all parties are over represented in these examples is because of the vote wasted on parties that did not cross the 5% threshold, this is particularly evident in 2008 where only the Green, National and Labour partes managed to win seats in Parliament.
FPP is completely un-proportional with the number of seats won having little to do with the share of the vote received, from 2002-2005 Labour’s vote dropped by 1 point this resulted in them losing 25% of the seats in parliament to National. Wild swings such as this are a feature of First Past the Post elections. Of course this is a two party system and no other party wins any seats between 1996 and 2008.
PV gives results very similar to FPP except that Labour does slightly better as they do not have to deal with the Alliance and Greens splitting their vote on the left, it is a two party system except for in 2002 when New Zealand First manage to win some representation, which they lose again in 2005. The freak result in 2005 in which a government was not able to be formed should not be seen as a product of the PV electoral system, it could happen in any of the proposed systems.
In this example SM returned a single party government in all the elections, while it does give minor parties representation they were unable to exert any influence on government. In all the elections the two largest parties were over represented while the smaller parties were under represented. Again large swings can be seen, although not as large as under FPP or PV, the 1 point decline in Labour’s vote between 2002 and 2005 results in them losing 19 % of parliament to National
Although STV comes very close to proportional results there are a few interesting results to note. Firstly Labour’s vote dropped from 2002 to 2005 yet their share of seats increased, also in 1996 United won a seat while the legalise cannabis party did not despite the ALCP winning 1.17% of the vote, this is because United Voters were more concentrated in Chartwell and the political positioning of United in between Labour and National meant that National voters supported United in order to keep Labour from winning an extra seat.
Method
I’m sure there are some people who are curious as too how I managed to run data from one electoral system through the others and all the distortions that result.
A large problem with what I have done is that I decided to treat every polling booth as a separate electorate which unfortunately means that the larger booths get the same representation as the smaller ones, which effectively gives National a slight advantage in all the options except for MMP.
For the preferential systems (PV and STV) I determined where votes went after candidates were eliminated by arranging the parties on a 2D spectrum from right to left and simply decided that half the votes would go the left of the preferred candidate and half to the right. This is obviously a very simplistic model of voter behavior but I feel that the result has been acceptable with perhaps a slight advantage to the center parties.
Probably the biggest issue with this project is that I had to assume that people would vote the same in differing political and electoral systems, this has led to a lot of wasted votes as the ACT, Māori, New Zealand First, Progressives and United Future parties received a greater share of the party vote than they probably would have if they did not have a safe electorate seat.
